New, used car what oil?

[DarkScorpion 10+ year member]

I would seafoam it then go with the synthetic

I would go with the Auto-RX treatment over using seafoam. Dozens upon dozens of people over at Maxima.org and Nissanclub.com have used it on their high mileage, older generation maximas with great success. I've used it personally and it definitely cleaned out some sludge from some of the older cars in my family.

In this situation, I'd just stick with dino. As was said earlier, synthetic might end up revealing some leaks you didn't know you had. That could be a good or bad thing depending on how you look at it. I prefer Pennzoil...

 

[Sleeklsc 5,000+ posts]

with that many miles and considering how old it is i'd hit up wally world and get a $10 5qt thing of oil (supertech??) and a fram filter that runs like 3 bucks..

 

[osl 10+ year member]

I would seafoam it then go with the synthetic

It wouldn't matter if you seafoamed or not. The purpose of synthetic is for it's protection. If a car used conventional all it's life, I don't think you can protect much at 200k. The only real advantage I see is that you could go 7k before changing your oil, even though I've gone 10k on full synthetic before changing with no problems. The way I see it, you change before that on full synthetic and you're wasting your money. Send me your used oil and I'll pour it right into my crankcase. Amsoil can be ran to 25k before changing and they'll guarantee it. Royal Purple is safe for 15-20k before changing. These are just to name a couple but from the tests I see, I'd stick with Royal Purple. Conventional oil doesn't matter to me. They are all the same IMO. Get the cheapest oil if you change every 3k anyways.

 

[audioholic 5,000+ posts]

You can change oil types (from regular to synthetic). It wont 'reveal' or create any leaks that weren't there already. The oil's viscosity is a measurement that reflects resistance to flow (and sheer), but it also is a measurement of predominant molecule size. The higher the viscosity rating, the larger the molecules. The larger the gap between parts (called tolerance), the larger the molecules of oil you want. But an engine with tighter tolerances would require a lower viscosity oil. So a 10W-30 conventional oil will have the same basic molecular size as a 10W-30 full synthetic, and you would experience no more oil loss through 'leaks' from either oil type.

What you cant do is mix convention motor oil and synthetic (like use one type, but top it off with the other). They break each other down chemically, and viscosity goes all to hell. If you switch from one type to the other, make sure you drain the old oil type as well as possible (dont skip changing the filter for example). And if you are really worried about it, just change your oil again within a few hundred miles to flush out the remains of the old oil type that mixed with the new when you did the first oil change.

 

[audioholic 5,000+ posts]

Oh, and I agree with the people who say on a car with that high of mileage, switching to synthetic motor oil now would just be a waste of money.

 

[BlactimusCrime 10+ year member]

DO NOT switch to synthetic or even semi synthetic oil, stick with a conventional or hight mileage conventional oil. You will use oil in one way or another if you switch it over now. I put a semi synthetic oil in my lincoln with 99k on it, and it started smoking, (blowing oil past the rings and burning it). its not a smart choice. Synthetic oil will reveal leaks or make your engine smoke.

 

[audioholic 5,000+ posts]

DO NOT switch to synthetic or even semi synthetic oil, stick with a conventional or hight mileage conventional oil. You will use oil in one way or another if you switch it over now. I put a semi synthetic oil in my lincoln with 99k on it, and it started smoking, (blowing oil past the rings and burning it). its not a smart choice. Synthetic oil with the wrong viscosity will reveal leaks or make your engine smoke.

Fixed.

 

[audioholic 5,000+ posts]

I guess I should take that back, Ive never switch to synthetic from conventional with vehicle that had 100k or more miles on it.

I wouldn't recommend bothering at that point anyway.

 

[BlactimusCrime 10+ year member]

My post needed no fixing. my car required 10w-30 oil and that is the weight synthetic oil i used. it smoked. problem: synthetic oil switch on an older motor. I know what im talking about, ask any seasoned mechanic and they will say the same thing i did.

the reason synthetic oil is a better lubricant is because it finds its way into every nook and cranny, this is also why it makes older motors smoke and leak, bc it finds its way into the already worn nooks and crannies and escapes thru them.

next time, before you "fix" someone's post, know wtf you're talking about.

 

[Slo_Ride 5,000+ posts]

The reason that switching to synthetic in an older engine that has always used conventional oil can cause leaks is that the build up of minor deposits actually helps prevent leaks around hardened seals and gaskets. Synthetic oils desolve this buildup then "creating" an oil leak. Running synthetic oil in a worn out engine is a waste, thats just the way it is.

 

[hatedonmostly 5,000+ posts]

The reason that switching to synthetic in an older engine that has always used conventional oil can cause leaks is that the build up of minor deposits actually helps prevent leaks around hardened seals and gaskets. Synthetic oils desolve this buildup then "creating" an oil leak. Running synthetic oil in a worn out engine is a waste, thats just the way it is.

THIS

I don't know why you people think putting synthetic in an old car is a waste if it gets more shit out of the system...

That's like electrical taping all of your connections on your system, and saying that spending the money on splice connectors or solder and heatshrink was a waste of money. wat

 

[audioholic 5,000+ posts]

next time, before you "fix" someone's post, know wtf you're talking about.

All I read was "blah blah blah, I didnt read your last reply, or I just really need someone to vent on".

THIS
I don't know why you people think putting synthetic in an old car is a waste if it gets more shit out of the system...it's not a big deal, as long as you're willing to change some gaskets that leak...

Piston rings.

 

[Slo_Ride 5,000+ posts]

THIS
I don't know why you people think putting synthetic in an old car is a waste if it gets more shit out of the system...

That's like electrical taping all of your connections on your system, and saying that spending the money on splice connectors or solder and heatshrink was a waste of money. wat

You missed it

 

[Slo_Ride 5,000+ posts]

I think half the folks here just want someone to argue with

 

[BlactimusCrime 10+ year member]

I think half the folks here just want someone to argue with

this.